Slider zippers are becoming very popular with consumers for use with reclosable consumer storage bags, such as freezer and sandwich bags. This popularity is the result of the relatively greater ease of opening and closing slider zippers, especially for the increasing population of older consumers that tend to have more trouble manipulating the typical press-to-lock zipper closures that are commonly found on storage bags.
The use of slider zippers has recently expanded to include bags that are sold containing retail items, such as food products, where it enjoys the same easy opening zipper advantage. Although the typical slider zipper is substantially more expensive, it can be particularly advantageous for use with packages that are sold containing retail items. When selling a bag containing a stored product, the total cost of the package including the stored product is much higher, and as a result it is easier to pass on the incremental cost of the slider zipper.
Other than the higher zipper cost, the most significant hindrance to the promotion of zippered packages with sliders has resulted from manufacturing difficulties that must be considered when attempting to make slider bags formed around a product, especially when using a vertical form, fill, and seal process for making such bags. Slider bags traditionally have been made adjacent to one of the package end seals. In the traditional arrangement, the slider element is secured to the outside of the package by connecting it over one side of the closure strips. In a typical form, fill process of making bags the adjacent bags remain connected at their ends, that is, the top of one bag is connected to the bottom of the next bag. This interconnection of bag ends makes it difficult to connect a slider over closure strips in the traditional manner when forming bags utilizing a typical form, fill, and seal process.
The present invention teaches a method of making a reclosable package that utilizes a zipper assembly that includes a slider element for ease of opening. and that overcomes the obstacles presented by the typical form, fill and seal process of making bags.
In accordance with the present invention, a method of making recloseable packages each having a slider zipper assembly is disclosed, with the method promoting efficient, high-speed manufacture and use of such packages in connection with a typical form, fill, and seal packaging process. Packages formed in accordance with the present invention offer the convenience of use of a fastener assembly having a slider element, and can be configured to provide a tamper-evident feature which functions in conjunction with movement of the fastener slider.
A method of making recloseable bags, each having a slider zipper assembly, in accordance with the present invention, comprises the steps of advancing a web of plastic film packaging material in a direction along a longitudinal axis thereof. The present method further includes applying a plurality of profile strip fastener assemblies to the plastic film material transversely of the longitudinal axis thereof. Each of the fastener assemblies comprises a pair of interlocking profile strips, with the fastener assemblies being spaced apart by a distance corresponding to the length of each of the recloseable packages being formed. Preferably, each of the profile strips includes a body portion, and a flange portion joined thereto. The body portions of the fastener assembly respectively include at least one cooperating, interlocking protuberance and groove arrangement for releaseably interconnecting the profile strips. Preferably, the flange portions of the profile strips extend in opposite directions from the respective body portions, thus facilitating efficient formation of the present package, including the necessary application of a slider to each fastener assembly.
The present method further includes the step of applying a slider to each of the fastener assemblies, so that movement of each slider along the length of the respective one of the fastener assemblies moves the pair of profile strips thereof into and out of interlocking engagement. The present process is completed by joining opposite side edges of the plastic film material to form a tube, and forming seals transversely of the tube to form a top seal and bottom seal for each of the packages.
One aspect of the present method which promotes efficiency is the manner in which the sliders are secured to the fastener assemblies during package formation. When package formation is effected in conjunction with use of a form, fill, and seal machine, the present method contemplates that the plastic film material is guided over a forming collar to shape the material into a generally tubular configuration prior to the step of joining opposite side edges of the material. In order to assure efficient movement of the plastic film material over the forming collar, it is preferred that the step of applying the slider assembly be performed after the step of guiding the plastic material over the forming collar. In the illustrated embodiment, the step of applying the slider is performed after the step of joining opposite side edges of the plastic film, but it will be understood that the slider could be applied before the side edges of the film are joined, but preferably after the film has been guided over the forming collar and shaped to a generally tubular configuration.
It is contemplated that the fastener assemblies are applied to a surface of the plastic film which becomes an inside surface of the tube, and that each slider is applied to the respective fastener assembly from a side of the plastic film opposite that surface. When configured in this fashion, it is contemplated that a frangible, tamper-evident region can be formed in the plastic film material for respective alignment with each fastener assembly. By this configuration, initial opening movement of the slider fractures the frangible region for tamper-evidence.
Each slider is configured to facilitate application to its respective fastener assembly without separation of the profile strips thereof. Each slider includes a pair of tapered walls for respective, interlocking sliding connection with the pair of profile strips of each fastener assembly. The profile strips are configured such that they are moved into and out of locking engagement with each other in directions generally parallel to a longitudinal axis of the package. This is in distinction from profile strips oriented such that the strips must be moved inwardly and outwardly with respect to each other for effecting engagement and disengagement.
A recloseable package having a slider zipper assembly configured in accordance with the present invention includes a rectangular plastic film web having side edges joined to each other to form a back seam, to thereby form a front wall and back wall of the package. The front and back walls are joined to each other at transversely extending seams at the top and bottom of the package.
A fastener assembly comprising a pair of interlocking profile strips is joined to the front wall of the package in spaced relationship to the end seam at the top of the package. A slider is applied to the fastener assembly so that movement of the slider along the length of the fastener assembly moves the profile strip into and out of interlocking engagement with each other in directions generally parallel to a longitudinal axis of the package. The fastener assembly is preferably joined to the inside surface of the front wall, with the front wall defining an opening in alignment with the slider for facilitating manipulation thereof.
To provide a tamper-evident feature, the front wall of the package can include a frangible, tamper-evident region in alignment with the fastener assembly, so that initial opening movement of the slider fractures the frangible region. The frangible region is selected from the group consisting of laser scoring, mechanical scoring, and perforations. Manufacture of the present package is facilitated by providing each of the profile strips of the fastener assembly with a body portion, and a flange portion having a width greater than the width of the respective body portion, with the fastener assembly being joined to the front wall by joining of the flange portion of each of the profile strips to the front wall. The flange portions of the profile strips preferably extend in opposite directions from the respective body portions.